The present invention relates to scroll-fluid equipment used for an air compressor, a vacuum pump or the like.
Such equipment is generally known, and has fixed and orbitally operating scroll components, each of which comprises an end plate and a scroll wrap protruding vertically therefrom. The fixed and orbitally operating scroll components are combined so that fluid chambers can be formed between the scroll wraps. The orbitally operating scroll component is revolved relative to the fixed scroll component without rotating itself, causing the fluid chambers to move continuously while their volumes vary.
In the scroll-fluid equipment above, since the fluid chamber moves radially toward the inner section of the scroll wrap while its volume is decreased to compress the fluid, the heat generated due to compression causes the scroll wrap to become hotter in its radially inner section than in its outer section. Thus, if the height of the scroll wrap of one of the scroll components is selected to have an appropriate axial gap between the scroll wrap and the end plate of the other scroll component during assembly, the radially inner section of the scroll wrap has its height increased during operation due to thermal expansion, thereby contacting and galling the end plate of the other scroll component.
A method for allowing the radially inner section of the scroll wrap to have a smaller height than its outer section to address the above problem has been known (for example, Japanese Patent Public Disclosure No. 58-67902). A scroll wrap with too small a height results in too large an axial gap between the scroll wrap and the end plate of the other scroll component, causing the leakage of fluid, while an insufficiently small height of a scroll wrap also may result in galling. No means have been provided to solve these two problems at the same time.